The finite reserves and combustion emissions of fossil fuels (i.e., petroleum, natural gas, and coal) as primary energy supplies pose severe challenges to future energy security. Renewable clean energy sources, such as solar and wind energy, are relatively cheap and abundant, and thus have been sought to address the shortcomings of fossil fuels. However, due to the intermittent operation and geographical limitations of renewable clean energy sources, there is a need for electrical energy storage (EES) devices to enable their wide implementation and implementation in portable forms. Batteries are well developed and successful EES devices. Lithium-ion batteries (LIBs) are commonly employed in consumer electronics, at least in part due to their high energy density. However, even state-of-the-art LIBs are not practical as a power source for transportation vehicles in the place of gasoline, as they exhibit a practical ˜150 Wh/kg in comparison to an at-least 300 Wh/kg desired for electric vehicles (EVs).
In addition to the development of next-generation LIBs, EES concepts beyond LIBs have been investigated. Lithium-sulfur (Li—S) batteries are among the most attractive EES options due to a theoretical energy density of 2500 Wh/kg. In addition, sulfur is abundant and cheap. However, pre-existing Li—S batteries suffer from many technical issues which prevent effective commercialization. Such technical issues include: (1) safety risks associated with the use of lithium metal as an anode, (2) the full utilization of sulfur-related active materials due to the insulating nature of sulfur and polysulfide species, and (3) the severe reduction of battery cycleability as a result of the shuttling of the active materials to the lithium metal anode due to the solubility of polysulfide species. Various strategies have been employed in an attempt to resolve these issues, and thereby make Li—S batteries a commercially viable technology. Among the employed strategies, Li2S was proposed as a replacement for S in order to avoid using lithium metal as anodes, and carbon-supported nanostructures were designed to improve the conductivities of S or Li2S. Attempts have also been made to depress the shuttling of S active materials to maintain the S active materials on the cathode to improve the cycleability of Li—S batteries, including employing porous and encapsulating matrices, various immobilizers (such as highly reactive functional groups and Cu nanoparticles), electrolyte additives (LiNO3), solid state electrolytes, aqueous/electrolyte dissolved polysulfide cathode, separator modification or new separator materials, new liquid electrolytes, aqueous binders, and surface coatings, among others. However, despite these efforts practical Li—S batteries employing microsized commercial Li2S or S were not produced.